Commonly practiced raising methods effect raising by allowing the textile to abrade against a brush, lightly oiled rotating sand paper roll or card cloth while the textile is kept dry and at room temperature. However, these methods entail the following problems: raising tends to be uneven because it is not easy to keep uniform contact pressure between the abrasive surface and textile. If uniform raising is intended, contact pressure must be as small as possible and contact times must be increased to an extreme extent, resulting in considerable lowering of productivity. Especially, in the case of polyester textiles, productivity is very low and the raised fibers easily cause pilling because of their high strength. Furthermore, uniformity and variety of the raised fibers are much inferior to textiles made of wool or cotton.
On the other hand, to improve the pilling resistance of a raised fabric, it is important to shear the raised fibers as short as possible. However, it is not only difficult to control the exact clearance between the cutting (shearing) knife and textiles, but also many factors which are difficult to control remain, such as sharpness of the cutting knife, shearing tension and textile thickness.
Recently, a method of raising in a dyeing machine with a special type of raising ring made of metal is disclosed in FIGS. 2 to 6 of Japanese Patent Publication No. 18556/76. This method has several improvements as compared with common practice as follows: friction coefficient is largely lowered in the liquid; contact times between the abrasive surface and textile are markedly increased by using a dyeing machine at high speed; and this method may be carried out in combination with dyeing.
However, in connection with achieving satisfactory and uniform raising efficiently, these methods have problems which still remain, in that the number and the length of the raised fibers cannot be easily controlled (the number is too small and the length is too large) and in that textiles are often broken before achieving sufficient raising because the raising ring has too coarse a surface. Moreover, the raising ring made of metal causes heavy abrasion, easily wears out and lacks resistance to chemical agents such as alkalis and acids which are often used in high temperature processing. Consequently, applications of these methods are extremely limited.